An ebonite beam B is rocked up and down rapidly by a train of mechanism, and moves the cranks FIG.
All cylinders drive on one crank-axle with three cranks at 120°.
The low-pressure cylinders drive on the leading crank-axle with cranks at right angles, the highpressure cylinders driving on the trailing wheels.
In this engine the two piston-rods of one side are not coupled to a common cross-head, but drive on separate cranks at an angle of 180°, the pair of 180° cranks on each side being placed at right angles.
When the four cranks are placed with two pairs at 180°, the pairs being at 90°, the forces are balanced without the introduction of a hammer-blow, but there remain large unbalanced couples, which if balanced by means of revolving weights in the wheels again reintroduce the hammerblow, and if left unbalanced tend to make the engine oscillate in a horizontal plane at high speed.